A front-end of a typical radio receiver, for example, a mobile telephone, typically includes one or more electronic integrated circuits or chips that include suitable amplifiers, filters, mixers, and other components. The integrated circuits or chips comprising suitable amplifiers, filters, mixers, and other components convert radio frequency (RF) signals provided to the front-end by an appropriate antenna into signals for use by other parts of the receiver. The other parts of the receiver typically include one or more chips. Generally, the parts of the receiver after the front-end require differential implementation. This is necessarily true for system on chip (SoC) scenarios which are characterized by a noisy environment and varied package requirements. Furthermore, radio frequency insertion packages (RFIP) which form part of a large SoC, have high substrate and supply/ground noise coupling into the radio frequency receiver front-end. Also, the noise coupling is unpredictable and cannot be simulated. Therefore, an RFIP having less sensitivity to noise coupling should be chosen. The RFIP must also be less sensitive against package parasitic capacitance on the supply side and the ground side.
Differential implementation involves utilizing differential signaling, wherein information is transmitted electrically by means of two complementary signals, sent on two separate wires. Differential signaling is used for both analog signaling, for example, audio systems, and digital signaling, for example, Ethernet, peripheral component interconnect (PCI) express, etc. Differential signaling is particularly preferred in RF circuits because of its tolerance to ground offsets. Since, at the end of a connection, a receiver reads the difference between two signals and the receiver ignores the incoming wires' voltages with respect to ground. Small changes in ground potential between a transmitter and a receiver do not affect the receiver's ability to efficiently detect the signal. Differential signaling also improves linearity, and the package parasitic capacitance on the supply side and the ground side become a common mode. In the common mode, the package parasitic capacitance on the supply side and the ground side are conducted in the same direction on both wires carrying the differential signal.
Front-end circuits with differential signaling implementation need a balun circuit for converting a single-ended signal to a differential signal and vice versa for the antenna interface in particular and generally for other blocks. A balun is conventionally implemented using an on-chip or an off-chip transformer. Transformers are relatively expensive, occupy board space, and require more discrete components. Furthermore, components required to implement an on-chip transformer are neither easily available nor well characterized in foundries. The components also induce loss in the front-end circuits. Accordingly, there is a long felt but unresolved need for a compact electronic balun circuit that precludes the need for a transformer.